>>664923>laptopHow many watts?
What is the output voltage on the AC/DC wall adapter?
If a folding solar panel isn't a viable solution then nothing will help you. Everything else weighs more. Your choices are,
solar panel (sun charging)
extra pre-charged batteries (charge at home before)
manual crank generator (hand power, leg power, water/wind, gravity, whatever its configuration)
thermoelectric (charge it via fire)
combustible fuel generator (propane, gasoline, kerosene, etc, noisy and smelly)
If it were me, I'd >>>diy up a super capacitor array to replace the laptop batteries, make a charge controller for it, and charge them manually in multiple ways,
The easiest and least problematic solution is using a 12v battery like for a car/motor bike/whatever in the size amp hour range/weight you want and a car charge adapter in the correct voltage for your laptop.
http://www.laptopchargerfactory.com/hp-compaq-pavilion-laptop-charger-car/pavilion-17-aRemember you'll need one of these for attaching your battery adapter to the battery,
http://www.thecpapshop.com/respironics-dc-battery-adapter-cable-1?gclid=CLyahMP2p8oCFQanaQodRTEJuQ>>665130Holy fuck, it is only a few cheap rechargeable batteries in there, lol